Wrathmonk
The only people who thought T45 was able to defend a naval force on it's own were the window-lickers in the Treasury and CS in the MoD who had to sell the "taking risk on retirement of SHAR". You'll note that none of the naval folk involved pretended for one minute that they were happy with the idea. Particularly now as we're only getting six T45, not the eight planned at the time.
A T45 has 48 Aster cells, which based on a couple per inbound allows 24 engagements. Nearly thirty years ago, a relatively unsophisticated force was capable of generating several waves of over twenty aircraft per day, sustained over a couple of weeks despite some fairly heavy losses. How long to empty the silos - particularly if your opponent is adept at feinting - ie forcing a SAM launch without pressing the attack? What if your RoE prevent use of PAAMS (or Sea Viper as we're now supposed to call it) in automatic mode?
The point about FW air is that it can identify inbounds and confirm intent, intercept to warn off, or spash if required. Most crucially of all, it allows you to kill the archer, not the arrow, which is usually the most efficient way of defence. All of this applies equally to aircraft defending land as well as a maritime force. From another perspective, one does not try to do SEAD by killing the SAM, you go after the launcher and the C2, similarly the artillery battery is the target, not the projectile if you want to counter artillery.
The point about a helo carrier & AV8As owning the airspace is that just by fitting a 20mm pod to the aircraft, you make it a lethal threat to a helo force, which cannot therefore probe beyond the cover of it's own force SAM (and deconfliction there would be a bitch). The naval force can therefore no longer see over the horizon - which reduces threat warning, decreases the arc a SAM ship can defend and generally makes the force AAWC very unhappy. This also allows threat air a lot more freedom in approach, flight plan etc all of which significantly reduces the effectiveness of the defences.
As for all JSF only doing strike, I suspect that reflects the single role mentality prevalent in some quarters. No-one really thinks Dave is just a bomb truck do they? Naval aircrew and aircraft are usually expected to operate in different roles, even if they don't necessarily excel in one. The ability of CVF to accommodate 30+ FW allows a small number to be allocated to deck alert or rotated through CAP, while the remainder deliver strike (or Surface Warfare, or OCA for that matter). The proportion allocated between DCA and other missions can vary according to the threat at the time. AD fighters can do OCA and escort strikes, they don't just sit and defend the ship 24/7. I assume the same applies to land-based air - some fighters are presumably tasked to defend strike aircraft bases when there is an air threat, surely?
Maritime forces need layered defences, FW & AEW to engage the threat at long range and kill it before the more complex problem (high-speed weaving missiles) becomes an issue. If it does, then that's what your SAM and CIWS systems do. Same applies to land, read E3, Ground-based radar,Tiffy and Rapier (what's left of it), plus rock apes for a different threat.
Hope that clarifies things.